AT&T Reservationless and Reserved Calls
Reservationless calls are available on-demand 24/7 and can support up to
125 users. Participants can join Reservationless calls via Toll-Free
numbers (U.S. only), Paid Dial-In (worldwide), Operator Assistance
(withToll-Free or Paid Dial-In), Host/Operator-Dialed, or a combination
of these methods. Reserved calls are available for 126 to 200 users, or calls that require special features.